1. Field of the Invention
The present invention relates to a display unit structure which is used for a display device of a portable information-processing device, such as a notebook personal computer.
2. Description of the Related Art
In recent years, the slim structure and the space saving are demanded for display units which are used as display devices of personal computers. With such demand, there is the tendency that the LCD (liquid crystal display) monitors which are excellent in the slim structure and the space saving are often used for the computer displays, rather than the CRT (cathode ray tube) monitors.
By the utilization of the display units having the slim structure, such as the LCD monitors, a portable information-processing device which is excellent in the slim structure and the space saving, such as a notebook personal computer, is accepted in the market.
Japanese Laid-Open Patent Application No. 2000-019978 discloses a display device of a portable information-processing device in which a front cosmetic plate made of a metallic material is used in order to increase the mechanical strength of the front cosmetic plate in the display device.
Moreover, Japanese Laid-Open Patent Application No. 2001-337621 discloses a flat liquid-crystal display unit in which a video-signal processing circuit board for a LCD monitor is fixed directly to the interior of the display unit, which makes it unnecessary to provide a dedicated supporting part for the circuit board.
FIG. 1 is a perspective exploded view of a conventional display unit structure. FIG. 2 is a cross-sectional view of the conventional display unit structure taken along the line II-II′ indicated in FIG. 1.
The display device of FIG. 1 is an example of a LCD display device of a notebook personal computer. As shown in FIG. 1, the LCD display device 20 generally is constructed by assembling of a front cosmetic plate 1, a display unit 2, an electronic part 3 associated with the display unit, mechanical parts 4 for mounting the display unit movably to the computer housing, and a cover 5.
As shown in FIG. 2, the LCD display device 20 in which the above components 1-5 are assembled together has a height that is equivalent to the total height of the front cosmetic plate 1, the display unit 2, and the cover 5.
However, the slim structure is demanded for display devices of portable information-processing devices. In order to satisfy such a demand, there is the tendency that the height of the display unit is made smaller through the years.
There are several methods for realizing the slim structure of the display device of the portable information-processing device. A typical one of such methods is to make the height of the LCD display unit smaller. For example, the typical method is directed to taking the two measures: making small the height of a glass plate used in the LCD display unit; and making small the height of a light-guide plate of a back light source in the LCD display unit.
FIG. 3 is a cross-sectional view of the conventional display unit structure of FIG. 1.
As shown in FIG. 3, the LCD display device includes a bezel 6, a glass plate 7, a multiple-layered optical sheet 8, a light-guide plate 9, a chassis 10, a printed circuit board 11, and a CCFL (cold cathode fluorescent lamp) 12.
In the LCD display device of FIG. 3, the bezel 6 generally is a component part for holding the peripheral edges of the glass plate 7. The bezel 6 is produced by molding, and the molding of the bezel 6 is bent downward at its end portions. The bezel 6 is arranged in a box-like formation so that the end surfaces of the chassis 10 are enclosed with the downward bent portions of the bezel 6. The light-guide plate 9, the optical sheet 8, and the glass plate 7 are arranged inside the chassis 10 by stacking them on the chassis 10 one by one.
The CCFL lamp 12 is disposed at the position within the base portion (the left-hand side of FIG. 3) of the chassis 10, where the lamp 12 confronts the incidence-side edge of the light-guide plate 9. The printed circuit board 11 is mounted beneath the back-side surface of the light-guide plate 9 in the vicinity of the edge portion (the right-hand side of FIG. 3) of the chassis 10.
The two measures taken by the above-mentioned mounting method are inadequate for realizing the slim structure of a display device of a portable information-processing device to some extent, and the unresolved problems still remain with the two measures. Namely, as for the measure of making small the height of the glass plate used in the LCD display device, it is difficult to ensure the mechanical strength of the glass plate at a desired level when the glass plate becomes thin. As for the measure of making small the height of the light-guide plate, it is difficult to ensure the brightness of the back-light lamp at a desired level when the light-guide plate becomes thin.